bpsk 调制解调的误码率Matlab仿真程序.doc

% *SIMULATION OF COEFFICIENTS OF RAYLEIGH FADING CHANNEL*% VEHICULAR SPEED, DOPPLER SHIFT% FADING COEFFICIENTS%* Num_path=2000; % Number of pathst=0.0001:10/Num_path:10; % Time rangef=150*10.6; % Carrier frequency (150 Mhz, 900 Mhz)wc=2*pi*f; vehicle_speed=100; % Speed of carkm/hrsv=vehicle_speed*5/18; % Receiver speedm/hrsc=300*103; % Speed of lightwm=wc*(v/c); % Maximum shiftfm=wm/(2*pi); % Doppler shift % SIMULATING ENSEMBLES OF SINUSOIDSfor i=1:Num_path A(i)=(2*pi/Num_path)*i; %Azimuthal angles wn(i)=wm*cos(A(i); phi(i)=(pi*i)/(Num_path+1); xc(i)=2*cos(wn(i)*t(i).*cos(phi(i)+cos(wm*t(i); xs(i)=2*cos(wn(i)*t(i).*sin(phi(i); T(i)=(1/(2*Num_path+1)0.5).*(xc(i)+j*xs(i);% Complex envelopeend; M=mean(abs(T); % MeanMdB=20*log10(M);TdB=floor(20*log10(abs(T); % Field dB % PLOTTING THE HISTOGRAMz1=hist(abs(T);z=hist(TdB,9);n=0;for k=1:9 n=n+z(k); end for j=1:9 P(j)=z(j)/n; end f(1)=P(1); for x=2:9 f(x)=f(x-1)+P(x); F(10-x)=f(x); endplot(z1); % Distribution charttitle(Rayleigh distribution);semilogy(t,abs(T)/max(abs(T),r) % Fading graphictitle(Received field);ylabel(Received field intensity);xlabel(time);grid on;%*BINARY PHASE SHIFT KEYING *% Simulation of BPSK system in presence of Additive White Guassian Noise% and Rayleigh fading and Dopper shift and using SPREAD SPECTRUM TECH%*DIRECT SEQUENCE SPREAD SEQUENCE*clear allclc f_data=1; % DATA FREQUENCYf_chip=11; % LENGTH OF CHIP SEQUENCEfc=220; % RELATIVE CARRIER FREQUENCYfs=fc*3; % SAMPLING FREQUENCYN=fs/f_chip; % CODING RATEdata_length=1000; M=2; % BINARY LEVEL CODING matches=0;errors=0;count=1; SNRpbit=0;SNR=SNRpbit;rand(state,12345); % INITIALISATION SEEDrandn(state,54321); numplot=100; msg_unspread=randsrc(data_length,1,0:M-1); % GENERATION OF RANDOM DATA PN_sequence=randsrc(11,1,0:1); % GENERATION OF PN SEQUENCE % GENERATION OF SPREADED MESSAGEj=1;for i = 1:data_length for k = j:j+f_chip msg_orig(k) = msg_unspread(i); end; msg_orig(j:(j+f_chip-1) = xor(msg_orig(j:(j+f_chip-1),PN_sequence(1:f_chip); j = f_chip*i+1; end; len_of_orig=length(msg_orig); % MODULATING THE SPREAD MESSAGE msg_tx=dmod(msg_orig,fc,f_chip,fs,psk,M);len_of_tx=length(msg_tx); % % RAYLEIGH COEFFICIENTS% magT=abs(T);% % % ADDING RAYLEGH FADING COEFFICIENTS% k=1;% for i=1:len_of_tx% msg_tx(1,i)=msg_tx(1,i)*10*magT(1,k);% if(mod(i,k)% k=k+300;% end ;% end; % PERFORMANCE ANALYSIS FOR VARYING SNRS for SNRpbit=0:1:7 SNR=SNRpbit; rand(state,12345); randn(state,54321); % ADDING AWGN TO THE SIGNAL msg_rx_data=awgn(msg_tx,SNR-10*log10(N),measured,dB); % plot(t,msg_rx(1:length(t),b-); msg_rx= msg_rx_data ; msg_rx=msg_tx; % DEMODULATING THE RECEIVED SIGNAL msg_demod=ddemod(msg_rx,fc,f_chip,fs,psk,M); % CORRELATING WITH THE PN SEQUENCE j=1; for i = 1:data_length msg_demod(j:(j+f_chip-1) = xor(msg_demod(j:(j+f_chip-1),PN_sequence(1:f_chip); j = f_chip*i+1; end; % DESPREADING THE RECEIVED SIGNAL j=1; for i = 1:data_length sum=0; for k = j:j+f_chip sum=sum+msg_demod(k); end; if (sum =7) msg_demod_rec(i)=1; else msg_demod_rec(i)=0; end; j = f_chip*i+1; end; % CALCULATION OF ERRORS for i=1:data_length; if (msg_demod_rec(1,i)= msg_unspread(i,1) matches=matches+1; else er